I took so much time fighting those stupid tanks with Quiet in MGS 5. I know I shouldn't have, but maybe I just suck.

I got here in the first attempt, i dropped some item on her with the idroid menu

I'm not talking about fighting against Quiet. I'm talking about the tanks you fight alongside Quiet.

Imperor Ing in Metroid Prime 2. He's such a pain even more than the Boost Ball Boss.

Vamp on MGS2... in Extreme.

I also remember The Mayor in Dead to Rights. That was rightfully annoying, especially since it was a rented game and had no time to complete it.

Seems someone didn't know about the railing trick!

Ornstein & Smough in Dark Souls.
Also Pontiff Sulyvahn (Dark Souls 3) was pretty tough.

The Crawler (or Al Bhed Gunner) in Final Fantasy X left me some painful memories too.

That goddam Brumack in Gears of War UE. It wouldn't have been so bad if Dom had ANY sense of self preservation but damn. I should have known he'd kill himself in Gears 3 because he was fucking suicidal in Gears 1!

The only way I won in single player is because, after 2000 tries, the boss glitched and got stuck on the background.

the other hunter guy that turned into a werewolf in Bloodborne, was the hardest out of all bossess in that game for me. The last boss on PC quantum break, I didn't know what to do but turned out really simple.

In Metal Gear solid 1 on PSX I had a hard time fighting a guy where you had to put your controller in the second port, who would do that lol.

Sephiroth in KH
The Orphan of Kos in Bloodborne, seriously dude makes Ludwing seem like a walk in the park.
Penance in the FFX remastered version
Yiazmat in FFXII - Tho it's more time consuming than hard
Almost every boss in Ninja Gaiden kicked my ass
Mike Tyson in Punch-Out I guess?
The first race against Wizpig in DKR
Several bosses in the good ol' megaman NES games.